The present invention relates to a semiconductor device and, for example, to a semiconductor device with an active clamp circuit.
A semiconductor device called IPD (Intelligent Power Device) which includes a high-side switch or a low-side switch that switches between supply and cutoff of a current to a load circuit and which turns the high-side switch or the low-side switch on and off in accordance with conditions is used. In the case where an inductive load such as a solenoid is included in a load circuit that is controlled by the IPD, when a current supplied to the load circuit is cut off by the IPD, an output voltage that is generated at a node that connects the IPD and the load circuit becomes higher than a power supply voltage in some cases. In order to prevent the breakdown of the IPD due to such an increase in the output voltage, a dynamic clamp circuit that limits an increase in the output voltage to a certain level is included in the IPD. An example of a semiconductor device that includes such a dynamic clamp circuit is disclosed in Japanese Unexamined Patent Publication No. 2000-200902.
In the semiconductor device that is described in Japanese Unexamined Patent Publication No. 2000-200902, a buffer is connected to a control input terminal, and the output of the buffer is input to the gate of an n-channel power MOS transistor through a resistor. Further, in the semiconductor device described in Japanese Unexamined Patent Publication No. 2000-200902, a load device is connected to a drain electrode of the n-channel power MOS transistor. In the semiconductor device described in Japanese Unexamined Patent Publication No. 2000-200902, a plurality of constant voltage diodes are connected in series, a cathode terminal of the last diode is connected to a drain electrode of the n-channel power MOS transistor 42, an anode terminal of the top diode of the plurality of constant voltage diodes connected in series is connected to an anode terminal of a general diode, and a cathode terminal of the general diode is connected to one end of the resistor and a gate electrode of the n-channel power MOS transistor.